Photonic crystal-enabled display stitching

ABSTRACT

A system, apparatus, and method include a first display device having a first set of pixels adapted to output light; a second display device having a second set of pixels adapted to output light; a first transparent plate spaced apart from each of the first display device and the second display device. The first transparent plate includes a first set of photonic crystal structures arranged in a first direction and adapted to deviate a first path of the light transmitted from the first and second set of pixels at a first angle. A second transparent plate is spaced apart from the first transparent plate and includes a second set of photonic crystal structures arranged in a second direction different from the first direction and adapted to deviate a second path of the light transmitted through the first transparent plate at a second angle to create a third path of light.

GOVERNMENT INTEREST

The invention described herein may be manufactured and used by or forthe Government of the United States for all government purposes withoutthe payment of any royalty.

BACKGROUND Field of the Invention

The embodiments herein generally relate to electronic display systems,and more particularly to projection displays for increased and enhancedviewing sizes.

Background of the Invention

In many cases, larger displays are desired than single televisionmonitors or computer monitors can provide. Similarly, for projectionsystems, larger format spatial light modulators (SLMs) such as lightemitting diode (LED) arrays, digital micro-mirror devices, etc. areoften desired but cost increases significantly with increased numbers ofpixel elements as fabrication yields decrease with size. In both cases,a desirable solution would use a method of “stitching” displays or SLMdevices together optically. However, simply butting devices against eachother allows much larger displays but has the highly undesirable effectof “seams” between displays such as television or monitor frames orelectronic addressing hardware.

This problem is illustrated in FIG. 1. The original image 5 is on theleft and it is desired to display the image 5 on a much larger display,beyond the limits of available televisions and monitors. By using fouror more smaller display devices 6 a-6 d, an overall larger display 6 canbe accomplished, but with an undesired “tiling” effect from the framesof the individual devices 6 a-6 d causing a segmented view of the image5. Accordingly, it would be desirable to achieve a larger display sizeof an image 5 without the undesired “tiling” effect.

BRIEF SUMMARY OF THE INVENTION

In view of the foregoing, an embodiment herein provides a systemcomprising a first display device comprising a first set of pixelsadapted to output light; a second display device comprising a second setof pixels adapted to output light; a first transparent plate spacedapart from each of the first display device and the second displaydevice, wherein the first transparent plate comprises a first set ofphotonic crystal structures arranged in a first direction and adapted todeviate a first path of the light transmitted from the first and secondset of pixels at a first angle; and a second transparent plate spacedapart from the first transparent plate and comprising a second set ofphotonic crystal structures arranged in a second direction differentfrom the first direction and adapted to deviate a second path of thelight transmitted through the first transparent plate at a second angleto create a third path of light.

The first display device may comprise a first frame that does notcontain the first set of pixels, and wherein the second display devicecomprises a second frame that does not contain the second set of pixels.The first display device and the second display device may be proximateto one another such that the first frame and the second frame arealigned to create an optical stitching plane that does not contain thefirst set of pixels and the second set of pixels. The optical stitchingplane may comprise an image viewing area overlapping a portion of thefirst frame and the second frame. The third path of light may permit adisplay of light in the image viewing area.

The first transparent plate and the second transparent plate may eachextend a combined length of the first display device and the seconddisplay device, and wherein the first set of photonic crystal structuresand the second set of photonic crystal structures are each discontinuousat the optical stitching plane. The first set of photonic crystalstructures may be arranged in the first direction is adapted to deviatethe first path of the light in a first angular deviation. The second setof photonic crystal structures may be arranged in the second directionis adapted to deviate the second path of the light in a second angulardeviation that is opposite to the first angular deviation. The firstangular deviation may be α for the first set of photonic crystalstructures and the second angular deviation may be −α for the second setof photonic crystal structures with respect to the first transparentplate and the second transparent plate arranged in front of the firstdisplay device. The first angular deviation may be −α for the first setof photonic crystal structures and the second angular deviation may be αfor the second set of photonic crystal structures with respect to thefirst transparent plate and the second transparent plate arranged infront of the second display device.

An apparatus comprising a first optically transparent substratecomprising a first set of photonic crystal structures adapted to deviatea first path of the light received from a first pair of discrete displaydevices; and a second optically transparent substrate spatially alignedwith the first optically transparent substrate and comprising a secondset of photonic crystal structures adapted to deviate a second path ofthe light transmitted through the first transparent substrate to createa third path of light. The junction of the first pair of discretedisplay devices may create an optical stitching plane, and wherein thefirst set of photonic crystal structures and the second set of photoniccrystal structures are discontinuous at the optical stitching plane.

The first optically transparent substrate may be adapted to receive thefirst path of light from a second pair of discrete display devices, andwherein first pair of discrete display devices and the second pair ofdiscrete display devices display a combined third path of light toinclude a region comprising the optical stitching plane. The firstoptically transparent substrate may be adapted to receive the first pathof light from multiple pairs of discrete display devices arranged in atwo-dimensional array. The first set of photonic crystal structures andthe second set of photonic crystal structures may be configured to haveopposite light deviation angles from each other. The first path of thelight received from a first device of the first pair of discrete displaydevices may be unaltered, and the first path of the light received froma second device of the first pair of discrete display devices may belaterally offset toward the first device.

Another embodiment provides a method of combining an output frommultiple display devices, the method comprising measuring a distancebetween a non-viewable display area between a pair of display devices;aligning a pair of optically transparent substrates with respect to thepair of display devices, wherein the pair of optically transparentsubstrates comprise a first optically transparent substrate and a secondoptically transparent substrate, wherein the first optically transparentsubstrate is positioned between the pair of display devices and a secondoptically transparent substrate, and wherein the pair of opticallytransparent substrates comprise photonic crystal structures; andoutputting light from the pair of display devices; and combining theoutput light from the pair of display devices in the non-viewabledisplay area upon projecting the output light through the aligned pairof optically transparent substrates.

The aligning may comprise calibrating a distance of the first opticallytransparent substrate to the pair of display devices. The aligning maycomprise calibrating a distance of the second optically transparentsubstrate to the first optically transparent substrate. The method maycomprise calibrating a light deviation angle of the photonic crystalstructures in the pair of optically transparent substrates. The methodmay comprise calibrating the light deviation angle to be betweenapproximately 15° to 20°. The method may comprise planarizing an outputplane of the pair of display devices.

These and other aspects of the embodiments herein will be betterappreciated and understood when considered in conjunction with thefollowing description and the accompanying drawings. It should beunderstood, however, that the following descriptions, while indicatingpreferred embodiments and numerous specific details thereof, are givenby way of illustration and not of limitation. Many changes andmodifications may be made within the scope of the embodiments hereinwithout departing from the spirit thereof, and the embodiments hereininclude all such modifications.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments herein will be better understood from the followingdetailed description with reference to the drawings, in which:

FIG. 1 is a schematic diagram illustrating a conventional approach toenlarging a display of an image;

FIG. 2 is a schematic diagram illustrating a system for enlarging thedisplay of an image, according to an embodiment herein;

FIG. 3 is a schematic diagram illustrating frames of the display devicesin the system of FIG. 2, according to an embodiment herein;

FIG. 4 is a schematic diagram illustrating an optical stitching plane inthe system of FIG. 2, according to an embodiment herein;

FIG. 5 is a schematic diagram illustrating an image viewing area in thesystem of FIG. 2, according to an embodiment herein;

FIG. 6 is a schematic diagram illustrating angular deviations of thepaths of light in the system of FIG. 2, according to an embodimentherein;

FIG. 7 is a schematic diagram illustrating an apparatus for enlarging animage, according to an embodiment herein;

FIG. 8 is a schematic diagram illustrating an optical stitching plane inthe apparatus of FIG. 7, according to an embodiment herein;

FIG. 9 is a schematic diagram illustrating transformations of paths oflight in the apparatus of FIG. 7, according to an embodiment herein;

FIG. 10 is a schematic diagram illustrating a two-dimensional array inthe apparatus of FIG. 7, according to an embodiment herein;

FIG. 11 is a schematic diagram illustrating different light deviationangles in the first and second photonic crystal structures in theapparatus of FIG. 7, according to an embodiment herein;

FIG. 12 is a schematic diagram illustrating an apparatus for outputtinglight, according to an embodiment herein;

FIG. 13A is a flow diagram illustrating a method of combining an outputfrom multiple display devices, according to an embodiment herein;

FIG. 13B is a flow diagram illustrating a method of calibrating adistance of a first substrate from a display device, according to anembodiment herein;

FIG. 13C is a flow diagram illustrating a method of calibrating adistance of a second substrate from a display device, according to anembodiment herein;

FIG. 13D is a flow diagram illustrating a method of calibrating a lightdeviation angle in photonic crystal structures, according to anembodiment herein;

FIG. 13E is a flow diagram illustrating a method of calibrating a lightdeviation angle at a specified range in photonic crystal structures,according to an embodiment herein; and

FIG. 13F is a flow diagram illustrating a method of planarizing anoutput plane in a pair of display devices, according to an embodimentherein.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the disclosed invention, its various features and theadvantageous details thereof, are explained more fully with reference tothe non-limiting embodiments that are illustrated in the accompanyingdrawings and detailed in the following description. Descriptions ofwell-known components and processing techniques are omitted to notunnecessarily obscure what is being disclosed. Examples may be providedand when so provided are intended merely to facilitate an understandingof the ways in which the invention may be practiced and to furtherenable those of skill in the art to practice its various embodiments.Accordingly, examples should not be construed as limiting the scope ofwhat is disclosed and otherwise claimed.

According to various examples, the embodiments herein provide atechnique for stitching the outputs of display devices such as computermonitors, televisions or spatial light modulators to create frame-less,large format displays. The stitching method utilizes photonic crystalsdeposited on an optically clear substrate. The photonic crystals deviatethe output of a display toward another display, and a second photoniccrystal structure on a second substrate deviates the output back to adirection parallel to the initial device output. The net result is alaterally offset apparent source location as desired. Each pair ofphotonic crystal structures has a first photonic crystal structure thatdeviates the light output by an angle α and a second photonic crystalstructure that provides an angular deviation of −α, compensating for thefirst photonic structure. The two pairs of photonic crystal structuresdiffer in that for the first device, the deviations are α then −α, butin the second device, the deviations are the opposite, namely, −α thenα. The outputs of two devices are optically stitched together along thevertical line separating the devices. In an example, a ray from each ofthe pixels closest to the device division is deviated at an abnormallywide angle from the last photonic crystal devices.

Referring now to the drawings, and more particularly to FIGS. 2 through13F where similar reference characters denote corresponding featuresconsistently throughout, there are shown exemplary embodiments. In thedrawings, the size and relative sizes of components, layers, and regionsmay be exaggerated for clarity.

FIG. 2 illustrates a system 10 comprising a first display device 15comprising a first set of pixels 20 adapted to output light 25. In someexamples, the first display device 15 may comprise a computer monitor,television monitor, or any other type of electronic display. In someexamples, the first display device 15 may comprise any of a liquidcrystal display (LCD), plasma, LED, organic light emitting diode (OLED),cathode ray tube (CRT), high definition (HD), ultra-high definition(UHD), and thin-film transistor (TFT) displays. In an example, the firstset of pixels 20 may comprise picture elements containing a combinationof red, green, blue, cyan, magenta, yellow, and black color intensities.The light 25 may be emitted in a substantially uniform manner or may bedirected non-uniformly according to various examples.

The system 10 comprises a second display device 30 comprising a secondset of pixels 35 adapted to output light 25. Similarly, in someexamples, the second display device 30 may comprise a computer monitor,television monitor, or any other type of electronic display. In someexamples, the first display device 15 may comprise any of a LCD, plasma,LED, OLED, CRT, HD, UHD, and TFT displays. In an example, the second setof pixels 35 may comprise picture elements containing a combination ofred, green, blue, cyan, magenta, yellow, and black color intensities.The light 25 may be emitted in a substantially uniform manner or may bedirected non-uniformly according to various examples.

The system 10 comprises a first transparent plate 40 spaced apart fromeach of the first display device 15 and the second display device 30.The spacing (e.g., distance) between the first transparent plate 40 andthe first display device 15 and the second display device 30 may be setto any suitable distance, which may be based, in part, on the type ofthe first display device 15 and the second display device 30 and theconfiguration (i.e., thickness, etc.) of the first transparent plate 40.Furthermore, the spacing may be adjusted either manually by a user or byan automated controller based on sensing a desired transmission of light25 through the first transparent plate 40. In some examples, the firsttransparent plate 40 may comprise glass, poly(methyl methacrylate)(PMMA), polyimide, plastic material, sapphire, polycarbonates, polymers,zinc-selenide, etc. The first transparent plate 40 may be flexible orrigid and may be configured at a sufficiently thin thickness (e.g., 1-4mm) to permit the light 25 to pass therethrough. The first transparentplate 40 comprises a first set of photonic crystal structures 45arranged in a first direction D₁ and adapted to deviate a first path P₁of the light 25 transmitted from the first and second set of pixels 20,35 at a first angle θ₁. The deviation of the first path P₁ of the light25 creates a second path P₂ of the light 25 from the first transparentplate 40. In some examples, the first set of photonic crystal structures45 may comprise any of periodic dielectric, metallo-dielectric, andsuperconductor microstructures or nanostructures, which may beconfigured as any of one-dimensional, two-dimensional, andthree-dimensional crystals.

The first direction D₁ is adapted to be uniform such that all of thecrystals in the first set of photonic crystal structures 45 in front ofthe first display device 15 are set to be positioned in a substantiallyuniform (e.g., the substantially same) direction (e.g., the firstdirection D₁). Moreover, the first direction D₁ is adapted to be uniformsuch that all of the crystals in the first set of photonic crystalstructures 45 in front of the second display device 30 are set to bepositioned in a substantially uniform (e.g., the substantially same)direction (e.g., the first direction D₁). However, the first directionD₁ corresponding to the first set of photonic crystal structures 45 infront of the first display device 15 is offset from the first directionD₁ corresponding to the first set of photonic crystal structures 45 infront of the second display device 30. This offset in the orientation ofthe first direction D₁ in the first set of photonic crystal structures45 may be accomplished by creating an area of discontinuity (furtherdescribed below) in the first transparent plate 40 to separate the firstset of photonic crystal structures 45 in front of the first displaydevice 15 and the first set of photonic crystal structures 45 in frontof the second display device 30.

The first path P₁ of light 25 is set to be substantially uniform (e.g.,the substantially same) direction. The direction or orientation of thefirst path P₁ of light 25 may be controlled by LED circuitry (notshown), for example, in the first display device 15 and second displaydevice 30. According to an example, the first angle θ₁ may be set at anysuitable angle such that there is a deviation in the first path P₁ oflight 25 transmitted from the first and second set of pixels 20, 35. Thedeviation of the first path P₁ of light 25 occurs as the light 25traverses through the first transparent plate 40, and the orientation ofthe first set of photonic crystal structures 45 arranged in a firstdirection D₁ is configured to cause the deviation of the first path P₁of light 25 as the light 25 hits the first set of photonic crystalstructures 45. The first angle θ₁ may be controlled based on theorientation of the first set of photonic crystal structures 45 in thefirst transparent plate 40. In an example, the first direction D₁ of thefirst set of photonic crystal structures 45 may be set to beunalterable. In another example, the first direction D₁ of the first setof photonic crystal structures 45 may be set to be alterable by applyingany of an electrical, magnetic, and electromagnetic signal to the firsttransparent plate 40 thereby causing a change in the orientation (e.g.,a change in the first direction D₁) of the first set of photonic crystalstructures 45 in the first transparent plate 40.

The system 10 comprises a second transparent plate 50 spaced apart fromthe first transparent plate 40 and comprising a second set of photoniccrystal structures 55 arranged in a second direction D₂ different fromthe first direction D₁ and adapted to deviate a second path P₂ of thelight 25 transmitted through the first transparent plate 40 at a secondangle θ₂ to create a third path P₃ of light 25. The second angle θ₂ maybe different from the first angle θ₁, and in an example the second angleθ₂ may be equal and opposite to the first angle θ₁. The spacing (e.g.,distance) between the second transparent plate 50 and the firsttransparent plate 40 may be set to any suitable distance, which may bebased, in part, on the respective configurations (i.e., thickness, etc.)of the first transparent plate 40 and the second transparent plate 50.Furthermore, the spacing may be adjusted either manually by a user or byan automated controller based on sensing a desired transmission of light25 through the first transparent plate 40 and the second transparentplate 50. In some examples, the second transparent plate 50 may compriseglass, PMMA, polyimide, plastic material, sapphire, polycarbonates,polymers, zinc-selenide, etc. The second transparent plate 50 may beflexible or rigid and may be configured at a sufficiently thin thickness(e.g., 1-4 mm) to permit the light 25 to pass therethrough. Therespective thicknesses of the first transparent plate 40 and the secondtransparent plate 50 may be the same or different from one another. Thesecond transparent plate 50 comprises a second set of photonic crystalstructures 55 arranged in a second direction D₂ and adapted to deviatethe second path P₂ of the light 25 from the first transparent plate 40at a second angle θ₂. The deviation of the second path P₂ of the light25 creates a third path P₃ of the light 25 from the second transparentplate 50. In some examples, the second set of photonic crystalstructures 55 may comprise any of periodic dielectric,metallo-dielectric, and superconductor microstructures ornanostructures, which may be configured as any of one-dimensional,two-dimensional, and three-dimensional crystals.

The second direction D₂ is adapted to be uniform such that all of thecrystals in the second set of photonic crystal structures 55 in front ofthe first display device 15 are set to be positioned in a substantiallyuniform (e.g., the substantially same) direction (e.g., the seconddirection D₂). Moreover, the second direction D₂ is adapted to beuniform such that all of the crystals in the second set of photoniccrystal structures 55 in front of the second display device 30 are setto be positioned in a substantially uniform (e.g., the substantiallysame) direction (e.g., the second direction D₂). However, the seconddirection D₂ corresponding to the second set of photonic crystalstructures 55 in front of the first display device 15 is offset from thesecond direction D₂ corresponding to the second set of photonic crystalstructures 55 in front of the second display device 30. This offset inthe orientation of the second direction D₂ in the second set of photoniccrystal structures 55 may be accomplished by creating an area ofdiscontinuity (further described below) in the second transparent plate50 to separate the second set of photonic crystal structures 55 in frontof the first display device 15 and the second set of photonic crystalstructures 55 in front of the second display device 30.

The second path P₂ of light 25 is set to be substantially uniform (e.g.,the substantially same) direction. The direction or orientation of thesecond path P₂ of light 25 may be controlled by LED circuitry (notshown), for example, in the first display device 15 and second displaydevice 30, which may be operatively connected to the first transparentplate 40. According to an example, the second angle θ₂ may be set at anysuitable angle such that there is a deviation in the second path P₂ oflight 25 from the first transparent plate 40. The deviation of thesecond path P₂ of light 25 occurs as the light 25 traverses through thesecond transparent plate 50, and the orientation of the second set ofphotonic crystal structures 55 arranged in a second direction D₂, whichis configured to be different than the orientation of the firstdirection D₁, and which is further configured to cause the deviation ofthe second path P₂ of light 25 as the light 25 hits the second set ofphotonic crystal structures 55. The second angle θ₂ may be controlledbased on the orientation of the second set of photonic crystalstructures 55 in the second transparent plate 50. In an example, thesecond direction D₂ of the second set of photonic crystal structures 55may be set to be unalterable. In another example, the second directionD₂ of the second set of photonic crystal structures 55 may be set to bealterable by applying any of an electrical, magnetic, andelectromagnetic signal to the second transparent plate 50 therebycausing a change in the orientation (e.g., a change in the seconddirection D₂) of the second set of photonic crystal structures 55 in thesecond transparent plate 50.

Each pair of photonic crystal structures (e.g., first set of photoniccrystal structures 45 and second set of photonic crystal structures 55)in front of the first display device 15 as well as each pair of photoniccrystal structures (e.g., first set of photonic crystal structures 45and second set of photonic crystal structures 55) in front of the seconddisplay device 30 has a first photonic crystal structure (e.g., firstset of photonic crystal structures 45) that deviates the light output bya deviation angle α (e.g., first angle θ₁, in an example) and a secondphotonic crystal structure (e.g., second set of photonic crystalstructures 55) that provides an angular deviation of −α (e.g., secondangle θ₂, in an example), compensating for the first set of photoniccrystal structures 45. As used herein, the deviation angle α maycorrespond to the first angle θ₁, and the deviation angle −α maycorrespond to the second angle θ₂, as further described with referenceto FIG. 6.

In an example, the two pairs of photonic crystal structures (e.g., firstset of photonic crystal structures 45 and second set of photonic crystalstructures 55) in front of the first display device 15 as well as eachpair of photonic crystal structures (e.g., first set of photonic crystalstructures 45 and second set of photonic crystal structures 55) in frontof the second display device 30 differ in that for the first set ofphotonic crystal structures 45 in front of the first display device 15,the deviations are α, and then −α for the second set of photonic crystalstructures 55. However, with respect to the second display device 30,the deviations are the opposite; namely, −α for the first set ofphotonic crystal structures 45 and then a for the second set of photoniccrystal structures 55.

FIG. 3, with reference to FIG. 2, illustrates that the first displaydevice 15 comprises a first frame 60 that does not contain the first setof pixels 20, and the second display device 30 comprises a second frame65 that does not contain the second set of pixels 35. For example, thefirst frame 60 and the second frame 65 may be structural housingcomponents of the first display device 15 and second display device 30,respectively. The configuration of the first frame 60 and the secondframe 65 of not containing the first set of pixels 20 and the second setof pixels 35, respectively, results in no light 25 being output from thefirst frame 60 and second frame 65, respectively.

FIG. 4, with reference to FIGS. 2 and 3, illustrates that the firstdisplay device 15 and the second display device 30 are proximate to oneanother such that the first frame 60 and the second frame 65 are alignedto create an optical stitching plane 70 that does not contain the firstset of pixels 20 and the second set of pixels 35. The outputs of twodevices (e.g., the first display device 15 and the second display device30) are optically stitched together along the optical stitching plane 70separating the first display device 15 and the second display device 30.At least one ray of light 25 from each of the pixels closest to thedevice division (e.g., optical stitching plane 70) is deviated at anabnormally wide angle (e.g., over 20°, for example) from the respectivefirst display device 15 and second display device 30. This leads to adrop in usable output radiance of pixels nearest the stitching line(e.g., optical stitching plane 70). Corrective compensation can beperformed in image generation. In an example, this process can beaccomplished with just a pair of photonic crystals (e.g., first set ofphotonic crystal structures 45 and second set of photonic crystalstructures 55) such that the light 25 output from the first displaydevice 15 is unaltered (e.g., no angular deviation of the light 25) andthe light 25 output from the second display device 30 is laterallyoffset toward the first display device 15.

FIG. 5, with reference to FIGS. 2 through 4, illustrates that theoptical stitching plane 70 comprises an image viewing area 75overlapping a portion 80 of the first frame 60 and the second frame 65.The third path P₃ of light 25 permits a display of light 25 in the imageviewing area 75 to permit a user to view an enlarged image projected byway of the output light 25. The first transparent plate 40 and thesecond transparent plate 50 each extend a combined length of the firstdisplay device 15 and the second display device 30. This configurationpermits all of the light 25 transmitted by the first display device 15and the second display device 30 to enter into the first transparentplate 40, and similarly into the second transparent plate 50. Moreover,this configuration permits the first transparent plate 40 and the secondtransparent plate 50 to include all display output optical energyprovided by the light 25 transmitted by the first display device 15 andthe second display device 30.

In an example, the first transparent plate 40 and the second transparentplate 50 may have the same length as each other. In another example, thefirst transparent plate 40 and the second transparent plate 50 may havea different length as each other. According to an embodiment herein, thefirst set of photonic crystal structures 45 and the second set ofphotonic crystal structures 55 are each discontinuous at the opticalstitching plane 70. Accordingly, there is a first discontinuous zone 41in the first transparent plate 40 and a second discontinuous zone 51 inthe second transparent plate 50 that align with the optical stitchingplane 70. This discontinuity at the optical stitching plane 70 permitsthe first set of photonic crystals 45 and the second set of photoniccrystals 55 to be configured at with different angular orientations α,−α depending on the position with respect to the first display device 15and the second display device 30.

The first set of photonic crystals 45 and second set of photoniccrystals 55 in the first transparent plate 40 and second transparentplate 50 are discontinuous at the optical stitching plane 70, with oneside having the negative angular deviation −α of the first angulardeviation α. Thus, both of the first set of photonic crystals 45 andsecond set of photonic crystals 55 both divert the display outputoptical energy toward the center (e.g., optical stitching plane 70) withthe same angular magnitude.

The first discontinuous zone 41 and the second discontinuous zone 51 atthe optical stitching plane 70 is where the deviation angles flip sign(e.g., from α to −α, or from −α to α). Furthermore, the second set ofphotonic crystals 55 in the second transparent plate 50 compensates forthe change in the path of the light 25 from the first path P₁ to thesecond path P₂ caused by the deviation caused by the first set ofphotonic crystals 45 in the first transparent plate 40, and accordinglythe second set of photonic crystals 55 in the second transparent plate50 returns the angular orientation of the light 25 to what it was priorto the first set of photonic crystals 45, but now, with a lateral offsetin position. The exception on the angle is the region (e.g., portion 80of the first frame 60 and the second frame 65) where energy from thefirst display device 15 extends to the photonic crystals associated withthe second display device 30.

In order for the first set of photonic crystals 45 and second set ofphotonic crystals 55 to have the beam diverting properties necessary,they are configured as spatially variant photonic crystals, which areself-collimating while re-directing energy at an angle of 90°. However,other, lower angular deviations are also possible using the sametechniques in accordance with the embodiments herein. Moreover, thefabrication methods for the first transparent plate 40 and the secondtransparent plate 50 are generally specific to the photonic crystaldesign selected.

To further illustrate the above concepts, FIG. 6, with reference toFIGS. 2 through 5, illustrates that the first set of photonic crystalstructures 45 arranged in the first direction D₁ is adapted to deviatethe first path P₁ of the light 25 in a first angular deviation α, andwherein the second set of photonic crystal structures 55 arranged in thesecond direction D₂ is adapted to deviate the second path P₂ of thelight in a second angular deviation −α that is opposite to the firstangular deviation α. The first angular deviation is α for the first setof photonic crystal structures 45 and the second angular deviation is −αfor the second set of photonic crystal structures 55 with respect to thefirst transparent plate 40 and the second transparent plate 50 arrangedin front 85 of the first display device 15. The first angular deviationis −α for the first set of photonic crystal structures 45 and the secondangular deviation is α for the second set of photonic crystal structures55 with respect to the first transparent plate 40 and the secondtransparent plate 50 arranged in front 90 of the second display device30.

FIG. 7, with reference to FIGS. 2 through 6, illustrates an apparatus100 comprising a first optically transparent substrate 105 comprising afirst set of photonic crystal structures 45 adapted to deviate a firstpath P₁ of the light 25 received from a first pair of discrete displaydevices 115. The light 25 may be emitted in a substantially uniformmanner or may be directed non-uniformly according to various examples.The apparatus 100 further comprises a second optically transparentsubstrate 120 spatially aligned with the first optically transparentsubstrate 105 and comprising a second set of photonic crystal structures55 adapted to deviate a second path P₂ of the light 25 transmittedthrough the first transparent substrate 105 to create a third path P₃ oflight 25. The spatial alignment (e.g., distance) between the firstoptically transparent substrate 105 and the second optically transparentsubstrate 120 may be set to any suitable distance, which may be based,in part, on the type of the first pair of discrete display devices 115and the configuration (i.e., thickness, etc.) of the first opticallytransparent substrate 105 and the second optically transparent substrate120. Furthermore, the spacing may be adjusted either manually by a useror by an automated controller based on sensing a desired transmission oflight 25 through the first optically transparent substrate 105 and thesecond optically transparent substrate 120.

The material for the first optically transparent substrate 105 and thesecond optically transparent substrate 120 may be chosen based on thespectrum of interest so that the substrates 105, 120 are opticallytransparent and compatible with photonic crystal fabrication. Someexample materials for the substrates 105, 120 may include (depending onwavelengths) but are not limited to glass, PMMA, polyimide, plasticmaterial, sapphire, polycarbonates, polymers, zinc-selenide, etc. Thefirst optically transparent substrate 105 and the second opticallytransparent substrate 120 may be flexible or rigid and may be eachconfigured at a sufficiently thin thickness (e.g., 1-4 mm) to permit thelight 25 to pass therethrough. The first pair of discrete displaydevices 115 may comprise a computer monitor, television monitor, or anyother type of electronic display. In some examples, the first pair ofdiscrete display devices 115 may comprise any of a LCD, plasma, LED,OLED, CRT, HD, UHD, and TFT displays. In some examples, the first set ofphotonic crystal structures 45 and the second set of photonic crystalstructures 55 may comprise any of periodic dielectric,metallo-dielectric, and superconductor microstructures ornanostructures, which may be configured as any of one-dimensional,two-dimensional, and three-dimensional crystals.

FIG. 8, with reference to FIGS. 2 through 7, illustrates that a junction125 of the first pair of discrete display devices 115 creates an opticalstitching plane 70, and wherein the first set of photonic crystalstructures 45 and the second set of photonic crystal structures 55 arediscontinuous at the optical stitching plane 70. According to anembodiment herein, the first set of photonic crystal structures 45 andthe second set of photonic crystal structures 55 are each discontinuousat the optical stitching plane 70. Accordingly, there is a firstdiscontinuous zone 141 in the first optically transparent substrate 105and a second discontinuous zone 151 in the second optically transparentsubstrate 120 that align with the optical stitching plane 70. Thisdiscontinuity at the optical stitching plane 70 permits the first set ofphotonic crystals 45 and the second set of photonic crystals 55 to beconfigured at with different angular orientations α, −α.

FIG. 9, with reference to FIGS. 2 through 8, illustrates that the firstoptically transparent substrate 105 is adapted to receive the first pathP₁ of light 25 from a second pair of discrete display devices 130. Thesecond pair of discrete display devices 130 may comprise a computermonitor, television monitor, or any other type of electronic display. Insome examples, the second pair of discrete display devices 130 maycomprise any of a LCD, plasma, LED, OLED, CRT, HD, UHD, and TFTdisplays. The first pair of discrete display devices 115 and the secondpair of discrete display devices 130 display a combined third pathP_(3(comb)) of light 25 to include a region 135 comprising the opticalstitching plane 70.

FIG. 10, with reference to FIGS. 2 through 9, illustrates that the firstoptically transparent substrate 105 is adapted to receive the first pathP₁ of light 25 from multiple pairs of discrete display devices 115, 130arranged in a two-dimensional array 140. Accordingly, thetwo-dimensional array 140 may contain multiple display devices arrangedto enhance the amount of light 25 being output for combination into thethird path P_(3(comb)) of light 25. While the drawings illustrate themultiple pairs of discrete display devices 115, 130 being arranged in aplanar configuration (e.g., straight) to form the two-dimensional array140, the embodiments herein may include an example where the multiplepairs of discrete display devices 115, 130 are arranged in a non-planarconfiguration. In an example, the first path P₁ of the light 25 receivedfrom a first device 145 of the first pair of discrete display devices115 is unaltered, and the first path P₁ of the light 25 received from asecond device 150 of the first pair of discrete display devices 115 islaterally offset toward the first device 145. Similarly, in an example,the first path P₁ of the light 25 received from a first device 146 ofthe second pair of discrete display devices 130 is unaltered, and thefirst path P₁ of the light 25 received from a second device 156 of thesecond pair of discrete display devices 130 is laterally offset towardthe first device 146.

FIG. 11, with reference to FIGS. 2 through 10, illustrates that thefirst set of photonic crystal structures 45 and the second set ofphotonic crystal structures 55 are configured to have opposite lightdeviation angles θ₁, θ₂ from each other. As used herein, the deviationangle α may correspond to the first angle θ₁, and the deviation angle −αmay correspond to the second angle θ₂. In an example, the first set ofphotonic crystal structures 45 and second set of photonic crystalstructures 55 in front of the first device 145 of the first pair ofdiscrete display devices 115 as well as the first set of photoniccrystal structures 45 and second set of photonic crystal structures 55in front of the second device 150 of the first pair of discrete displaydevices 115 differ in that for the first set of photonic crystalstructures 45 in front of the first device 145, the deviations are α,and then −α for the second set of photonic crystal structures 55.However, with respect to the second device 150, the deviations are theopposite; namely, −α for the first set of photonic crystal structures 45and then a for the second set of photonic crystal structures 55.

FIG. 12, with reference to FIGS. 2 through 11, illustrates an apparatus200 for combining an output 230 from multiple display devices 205, 210.There is a distance d between a non-viewable display area 215 and a pairof display devices 205, 210. The pair of display devices 205, 210 maycomprise a computer monitor, television monitor, or any other type ofelectronic display. In some examples, the pair of display devices 205,210 may comprise any of a LCD, plasma, LED, OLED, CRT, HD, UHD, and TFTdisplays. A pair of optically transparent substrates 105, 120 arealigned with respect to the pair of display devices 205, 210. The pairof optically transparent substrates 105, 120 comprise a first opticallytransparent substrate 105 and a second optically transparent substrate120. The first optically transparent substrate 105 is positioned betweenthe pair of display devices 205, 210 and a second optically transparentsubstrate 120. The pair of optically transparent substrates 105, 120comprise photonic crystal structures 220, 221, respectively. In someexamples, the photonic crystal structures 220, 221 may comprise any ofperiodic dielectric, metallo-dielectric, and superconductormicrostructures or nanostructures, which may be configured as any ofone-dimensional, two-dimensional, and three-dimensional crystals. Thepair of display devices 205, 210 comprise an output plane 225. Light 25is output from the pair of display devices 205, 210. The light 25 iscombined from the pair of display devices 205, 210 in the non-viewabledisplay area 215 upon projecting the output light 25 through the alignedpair of optically transparent substrates 105, 120.

The process described above is for stitching of two displays devices205, 210. However, multiple display stitching can be accomplished in aconsecutive manner and stitching can be performed in any direction andfor any number of display devices. The results of those two stitchingoperations are then stitched together to yield more than two devicestitched output. Odd numbers of outputs are possible in the same way.Likewise, stitching in two dimensions is possible with photonic crystalsdesigned for angular offset in the resultant direction of the twoindividual desired offsets.

FIG. 13A, with reference to FIGS. 2 through 12, is a flow diagramillustrating a method 300 of combining an output 230 from multipledisplay devices 205, 210, the method 300 comprising measuring (305) adistance d between a non-viewable display area 215 between a pair ofdisplay devices 205, 210. The measuring (305) may occur manually orusing sensors (not shown) operatively connected to the multiple displaydevices 205, 210, and calculated using a processor (not shown).

The method 300 comprises aligning (310) a pair of optically transparentsubstrates 105, 120 with respect to the pair of display devices 205,210. The pair of optically transparent substrates 105, 120 comprise afirst optically transparent substrate 105 and a second opticallytransparent substrate 120. The first optically transparent substrate 105is positioned between the pair of display devices 205, 210 and a secondoptically transparent substrate 120. The pair of optically transparentsubstrates 105, 120 comprise photonic crystal structures 220, 221. Themethod 300 comprises outputting (315) light 45 from the pair of displaydevices 205, 210. The light 25 may be emitted in a substantially uniformmanner or may be directed non-uniformly according to various examples.The method 300 comprises combining (320) the output light 25 from thepair of display devices 205, 210 in the non-viewable display area 215upon projecting the output light 25 through the aligned pair ofoptically transparent substrates 105, 120.

FIG. 13B, with reference to FIGS. 2 through 13A, is a flow diagramillustrating that in the method 300, the process of aligning (310)comprises calibrating (325) a distance of the first opticallytransparent substrate 105 to the pair of display devices 205, 210. In anexample, the process of calibrating (325) may occur manually or usingsensors (not shown) operatively connected to the multiple displaydevices 205, 210, and calculated using a processor (not shown). Thedistance between the first optically transparent substrate 105 and thepair of display devices 205, 210 may be adjusted accordingly. Theadjustment may be based, in part, on the type of the pair of displaydevices 205, 210 and the configuration (i.e., thickness, etc.) of thefirst optically transparent substrate 105.

FIG. 13C, with reference to FIGS. 2 through 13B, is a flow diagramillustrating that in the method 300, the process of aligning (310)comprises calibrating (330) a distance of the second opticallytransparent substrate 120 to the first optically transparent substrate105. In an example, the process of calibrating (330) may occur manuallyor using sensors (not shown) operatively connected to the multipledisplay devices 205, 210, and calculated using a processor (not shown).The distance between the first optically transparent substrate 105 andthe second optically transparent substrate 120 may be adjustedaccordingly. The adjustment may be based, in part, on the configuration(i.e., thickness, etc.) of the first optically transparent substrate 105and the second optically transparent substrate 120.

FIG. 13D, with reference to FIGS. 2 through 13C, is a flow diagramillustrating the method 300 comprises calibrating (335) a lightdeviation angle α of the photonic crystal structures 220 in the pair ofoptically transparent substrates 105, 120. In an example, thecalibration of the light deviation angle α may occur by applying any ofan electrical, magnetic, and electromagnetic signal to the pair ofoptically transparent substrates 105, 120 thereby causing a change inthe orientation (e.g., a change in the light deviation angle α or −α) ofthe photonic crystal structures 220, 221 in the pair of opticallytransparent substrates 105, 120, respectively.

FIG. 13E, with reference to FIGS. 2 through 13D, is a flow diagramillustrating the method 300 comprises calibrating (340) the lightdeviation angle α to be between approximately 15° to 20°, according toone example. In other embodiments, the light deviation angle α may be atother suitable angles based on the calibration process and/or a desireduser preference. For example, the light deviation angle α may be 80° ormore, in other embodiments.

FIG. 13F, with reference to FIGS. 2 through 13E, is a flow diagramillustrating the method 300 comprises planarizing (345) an output plane225 of the pair of display devices 205, 210. In this regard, the outputplane 225 may be configured to be perpendicular and straight withrespect to the pair of display devices 205, 210 to ensure that the pairof display devices 205, 210 are not rotated with respect to a userpositioned in front of the second optically transparent substrate 120 topermit as clear an image as possible for viewing.

The embodiments herein provide a technique for optically combining(“stitching”) two or more displays (monitors, televisions, etc.) orspatial light modulators (SLMs) in such a way that their frames are notvisible in the final output. This allows for small format, low cost SLMsto be effectively combined into large format SLMs with much lower totalcost than a comparable single large format device (if fabrication waspossible at all). Similarly, large area displays could be accomplishedbeyond the limit of current monitor sizes (around 90 inch). Thestitching method allows for stitching of two devices at a time, but canbe cascaded to stitch more than two devices.

The embodiments herein utilize a novel application of photonic crystalsto redirect outputs of monitors in such a way that the active pixelregions of each device (SLM, monitor, etc.) are made adjacent to eachother without a hard frame around each device. In the event there is anoutput radiance dropoff near the edges of the devices that are beingstitched, this dropoff, which can reach 50%, can be compensated byoperating the remainder of the device at half power with the decreasedradiance regions being operated at full power (or as appropriate) tomake the total output uniform. This may cause the device to effectivelylose half of its output power. Rather than operating at low power ascompensation, the region of stitching can be tolerated as a slightlydarker band if permitted.

The foregoing description of the specific embodiments will so fullyreveal the general nature of the embodiments herein that others can, byapplying current knowledge, readily modify and/or adapt for variousapplications such specific embodiments without departing from thegeneric concept, and, therefore, such adaptations and modificationsshould and are intended to be comprehended within the meaning and rangeof equivalents of the disclosed embodiments. It is to be understood thatthe phraseology or terminology employed herein is for the purpose ofdescription and not of limitation. Those skilled in the art willrecognize that the embodiments herein can be practiced with modificationwithin the spirit and scope of the appended claims.

What is claimed is:
 1. A system comprising: a first display devicecomprising a first set of pixels adapted to output light; a seconddisplay device comprising a second set of pixels adapted to outputlight; a first transparent plate spaced apart from each of the firstdisplay device and the second display device, wherein the firsttransparent plate comprises a first set of photonic crystal structuresarranged in a first direction and adapted to deviate a first path of thelight transmitted from the first and second set of pixels at a firstangle; and a second transparent plate spaced apart from the firsttransparent plate and comprising a second set of photonic crystalstructures arranged in a second direction different from the firstdirection and adapted to deviate a second path of the light transmittedthrough the first transparent plate at a second angle to create a thirdpath of light.
 2. The system of claim 1, wherein the first displaydevice comprises a first frame that does not contain the first set ofpixels, and wherein the second display device comprises a second framethat does not contain the second set of pixels.
 3. The system of claim2, wherein the first display device and the second display device areproximate to one another such that the first frame and the second frameare aligned to create an optical stitching plane that does not containthe first set of pixels and the second set of pixels, and wherein theoptical stitching plane comprises an image viewing area overlapping aportion of the first frame and the second frame.
 4. The system of claim3, wherein the third path of light permits a display of light in theimage viewing area.
 5. The system of claim 3, wherein the firsttransparent plate and the second transparent plate each extend acombined length of the first display device and the second displaydevice, and wherein the first set of photonic crystal structures and thesecond set of photonic crystal structures are each discontinuous at theoptical stitching plane.
 6. The system of claim 1, wherein the first setof photonic crystal structures arranged in the first direction isadapted to deviate the first path of the light in a first angulardeviation, and wherein the second set of photonic crystal structuresarranged in the second direction is adapted to deviate the second pathof the light in a second angular deviation that is opposite to the firstangular deviation.
 7. The system of claim 6, wherein the first angulardeviation is α for the first set of photonic crystal structures and thesecond angular deviation is −α for the second set of photonic crystalstructures with respect to the first transparent plate and the secondtransparent plate arranged in front of the first display device.
 8. Thesystem of claim 6, wherein the first angular deviation is −α for thefirst set of photonic crystal structures and the second angulardeviation is α for the second set of photonic crystal structures withrespect to the first transparent plate and the second transparent platearranged in front of the second display device.
 9. An apparatuscomprising: a first optically transparent substrate comprising a firstset of photonic crystal structures adapted to deviate a first path ofthe light received from a first pair of discrete display devices; and asecond optically transparent substrate spatially aligned with the firstoptically transparent substrate and comprising a second set of photoniccrystal structures adapted to deviate a second path of the lighttransmitted through the first transparent substrate to create a thirdpath of light.
 10. The apparatus of claim 9, wherein a junction of thefirst pair of discrete display devices creates an optical stitchingplane, and wherein the first set of photonic crystal structures and thesecond set of photonic crystal structures are discontinuous at theoptical stitching plane.
 11. The apparatus of claim 10, wherein thefirst optically transparent substrate is adapted to receive the firstpath of light from a second pair of discrete display devices, andwherein first pair of discrete display devices and the second pair ofdiscrete display devices display a combined third path of light toinclude a region comprising the optical stitching plane.
 12. Theapparatus of claim 11, wherein the first optically transparent substrateis adapted to receive the first path of light from multiple pairs ofdiscrete display devices arranged in a two-dimensional array.
 13. Theapparatus of claim 9, wherein the first set of photonic crystalstructures and the second set of photonic crystal structures areconfigured to have opposite light deviation angles from each other. 14.The apparatus of claim 9, wherein the first path of the light receivedfrom a first device of the first pair of discrete display devices isunaltered, and wherein the first path of the light received from asecond device of the first pair of discrete display devices is laterallyoffset toward the first device.
 15. A method of combining an output frommultiple display devices, the method comprising: measuring a distancebetween a non-viewable display area between a pair of display devices;aligning a pair of optically transparent substrates with respect to thepair of display devices, wherein the pair of optically transparentsubstrates comprise a first optically transparent substrate and a secondoptically transparent substrate, wherein the first optically transparentsubstrate is positioned between the pair of display devices and a secondoptically transparent substrate, and wherein the pair of opticallytransparent substrates comprise photonic crystal structures; andoutputting light from the pair of display devices; and combining theoutput light from the pair of display devices in the non-viewabledisplay area upon projecting the output light through the aligned pairof optically transparent substrates.
 16. The method of claim 15, whereinthe aligning comprises calibrating a distance of the first opticallytransparent substrate to the pair of display devices.
 17. The method ofclaim 15, wherein the aligning comprises calibrating a distance of thesecond optically transparent substrate to the first opticallytransparent substrate.
 18. The method of claim 15, comprisingcalibrating a light deviation angle of the photonic crystal structuresin the pair of optically transparent substrates.
 19. The method of claim18, comprising calibrating the light deviation angle to be betweenapproximately 15° to 20°.
 20. The method of claim 15, comprisingplanarizing an output plane of the pair of display devices.